Micro-truss structures, such as those disclosed in the '989 patent, have numerous applications. The fabrication method disclosed in the '989 patent involves forming micro-truss structures by exposing a suitable liquid photomonomer to collimated light through one or more photomasks. Such a liquid photomonomer may undergo a refractive index change during a photo-polymerization process, which may lead to a formation of polymer optical waveguides. If a monomer that is photo-sensitive is exposed to light (e.g., ultraviolet (UV) light) under the right conditions, the initial area of polymerization, such as a small circular area, will “trap” the light and guide it to the tip of the polymerized region, further advancing that polymerized region. This process will continue, leading to the formation of a waveguide structure with approximately, or about, the same cross-sectional dimensions along its entire length. A photomask with a two-dimensional pattern of apertures may be used to create a three-dimensional polymer microstructure, when a tray of photomonomer is illuminated from above, through the photomask, by collimated light from several different directions.
A micro-truss structure may be formed from the top down, by illuminating the liquid photomonomer to collimated light from above, through one or more photomasks positioned above the liquid photomonomer.
In some circumstances it may be advantageous to grow a micro-truss structure from the bottom up, and, thus, there is a need for a system for forming a micro-truss structure from the bottom up.